Operators and MVNOs are once again striving to offer mobile plans offering enough data at attractive rates. Cdiscount Mobile and Coriolis both currently offer 4G plans with 30 GB of data at €6.99/month, and with 8 GB of data from Europe and the overseas departments. For this rate, you are entitled to unlimited calls and SMS/MMS in mainland France and from the EU/DOM.
Note that Cdiscount Mobile uses the Bouygues Telecom network while Coriolis relies on the SFR network.
If you are looking for mobile plans for less than €5/month:
If you are looking for 5G plans at low prices: